Model comparison
Grok 4 Fast vs o3
o3 is the stronger model overall, scoring 47.5 to 39.4 on the Noometry Index.
Last verified . 26 shared benchmarks.
Summary
- They share 26 benchmarks with published results for both. Grok 4 Fast scores higher in 2 categories and o3 in 7 categories; 7 gaps are clear of the uncertainty.
- The widest gap is in knowledge, where o3 leads 54.6 to 32.0.
- The biggest single-benchmark swing is ARC-AGI-1: 48.5% for Grok 4 Fast and 60.8% for o3.
Side by side
| Grok 4 Fast | o3 | |
|---|---|---|
| Provider | xAI | OpenAI |
| Noometry Index | 39.4 | 47.5 |
| Released | 2025-09-19 | 2025-04-16 |
| Weights | Proprietary | Proprietary |
| Context window | — | 200K |
| Max output | — | 100K |
| Input $ / M tokens | — | $2 |
| Output $ / M tokens | — | $8 |
| Results tracked | 30 | 63 |
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Category by category
Coding o3 leads
Grok 4 Fast: 32.5 (#271), o3: 46.8 (#64)
| Benchmark | Grok 4 Fast | o3 |
|---|---|---|
| WeirdML | 42.9% | 52.4% |
| LMArena Coding | 1429 | 1408 |
| SWE-bench Verified | — | 62.3% |
| SWE-bench Verified (bash only) | — | 58.4% |
| Aider Polyglot | — | 81.3% |
| LMArena WebDev | 1159 | — |
| GSO | — | 8.8% |
| CadEval | — | 74% |
| ALE-Bench | — | 933.55 |
Agentic & Tool Use o3 leads
Grok 4 Fast: 29.5 (#86), o3: 34.5 (#44)
| Benchmark | Grok 4 Fast | o3 |
|---|---|---|
| LMArena Search | 1171 | 1144 |
| Berkeley Function Calling Leaderboard | — | 63% |
| GDPval | — | 30.8% |
| τ²-bench Banking | 15.7% | — |
| Cybench | 30% | — |
| DeepResearch Bench | — | 45.2% |
| OSWorld | — | 23% |
| METR Time Horizons | — | 65.4% |
Reasoning o3 leads
Grok 4 Fast: 22.2 (#201), o3: 32.0 (#78)
| Benchmark | Grok 4 Fast | o3 |
|---|---|---|
| ARC-AGI-2 | 5.3% | 6.5% |
| Kagi LLM Benchmark | 66.1% | 67.6% |
| ARC-AGI-1 | 48.5% | 60.8% |
| LMArena Hard Prompts | 1412 | 1402 |
| DTBench | 82.7% | 84.8% |
| Epoch Capabilities Index | 144.2 | 146.86 |
| ForecastBench | 60.5 | 62.5 |
| SimpleBench | — | 53.1% |
| CritPt | — | 1.4% |
| Chess Puzzles | — | 38% |
| EnigmaEval | — | 13.1% |
| Mystery Game Puzzles | — | 29% |
| LMCA | — | 39.7% |
Math o3 leads
Grok 4 Fast: 38.9 (#123), o3: 50.2 (#58)
| Benchmark | Grok 4 Fast | o3 |
|---|---|---|
| LMArena Math | 1419 | 1426 |
| FrontierMath (Tiers 1-3) | — | 33.3% |
| OTIS Mock AIME 2024-2025 | — | 84.4% |
| Omni-MATH | — | 71.4% |
| MATH Level 5 | — | 97.8% |
| FrontierMath (Feb 2025 set) | — | 18.7% |
| FrontierMath Tier 4 (v1) | — | 2.1% |
Knowledge o3 leads
Grok 4 Fast: 32.0 (#214), o3: 54.6 (#52)
| Benchmark | Grok 4 Fast | o3 |
|---|---|---|
| LMArena Expert | 1411 | 1402 |
| GPQA Diamond | — | 81.8% |
| Humanity's Last Exam | — | 20.3% |
| SimpleQA Verified | — | 49.4% |
| MMLU-Pro | — | 85.9% |
| Confabulations | — | 14.4% |
| Vectara Hallucination Rate | 19.7% | — |
| GPQA (HELM) | — | 75.3% |
Multimodal Not comparable
Grok 4 Fast: —, o3: 41.4 (#36)
| Benchmark | Grok 4 Fast | o3 |
|---|---|---|
| LMArena Vision | — | 1214 |
| GeoBench | — | 74% |
| VPCT | — | 52% |
Multilingual Too close to call
Grok 4 Fast: 51.3 (#111), o3: 51.7 (#105)
| Benchmark | Grok 4 Fast | o3 |
|---|---|---|
| LMArena Non-English | 1396 | 1401 |
| LMArena Chinese | 1457 | 1437 |
| LMArena French | 1431 | 1430 |
| LMArena German | 1383 | 1420 |
| LMArena Japanese | 1352 | 1403 |
| LMArena Korean | 1357 | 1370 |
| LMArena Russian | 1389 | 1406 |
| LMArena Spanish | 1415 | 1395 |
Instruction Following Too close to call
Grok 4 Fast: 73.2 (#121), o3: 72.8 (#127)
| Benchmark | Grok 4 Fast | o3 |
|---|---|---|
| LMArena Instruction Following | 1387 | 1368 |
| IFEval | — | 86.9% |
Long Context Grok 4 Fast leads
Grok 4 Fast: 63.2 (#3), o3: 53.3 (#6)
| Benchmark | Grok 4 Fast | o3 |
|---|---|---|
| Fiction.LiveBench | 94.4% | 88.9% |
| LMArena Longer Query | 1415 | 1372 |
| CL-bench | — | 17.8% |
Writing & Preference o3 leads
Grok 4 Fast: 60.0 (#102), o3: 63.5 (#64)
| Benchmark | Grok 4 Fast | o3 |
|---|---|---|
| LMArena Text | 1407 | 1410 |
| LMArena Creative Writing | 1387 | 1359 |
| LMArena Multi-Turn | 1414 | 1405 |
| Short-Story Creative Writing | — | 83.9% |
| EQ-Bench Creative Writing | — | 1676 |
| WildBench | — | 86.1% |
Frequently asked questions
Is Grok 4 Fast better than o3?
o3 is the stronger model overall, scoring 47.5 to 39.4 on the Noometry Index.
Is Grok 4 Fast or o3 better for coding?
o3 scores higher on coding benchmarks: 46.8 versus 32.5 in the Noometry coding category.
How many benchmarks do Grok 4 Fast and o3 share?
26 benchmarks have published results for both models. Grok 4 Fast has 30 scored results on Noometry and o3 has 63.